The present invention is particularly applicable for use in a container of welding wire stored as a large wire stack or coils or wire containing convolutions formed into layers of the welding wire which is paid out from the wire stack or coils through the upper portion of the container storing the wire stack or coils. However, the invention has broader applications and may be used with any type of welding wire contained in a wire stack or coils to be fed from the wire stack or coils through the top of the container with or without a tendency to retain a generally straight condition.
Welding wire is often shipped in a cylindrical drum which includes a cylindrical inner core. When it is desired to use the wire, a cone assembly is mounted at the top of the container. The cone assembly includes a payout arm extending upwardly from the top of the cone that is provided with an eyelet at its end and a central conduit for guiding the wire to a wire feeder mechanism.
When welding automatically or semi-automatically, it is essential that large amounts of welding wire be continuously directed to the welding operation in a non-twisted, non-distorted non-canted condition so that the welding operation is performed uniformly over long periods of time without manual intervention and/or inspection. It is a tremendously difficult task to be assured that the wire is fed to the welding operation in a non-twisted condition so that the natural tendency of the wire to seek a preordained natural condition will not be detrimental to smooth and uniform welding.
To accomplish this task, welding wire is produced to have a no-twist condition. Welding wire has a cast that is intentionally built into the wire when its is manufactured. The nature shape of the wire is not straight, but typically sinusoidal. A straight welding wire has difficulty in making reliable contact with the contact tip of a welding gun so as to properly pass current through the wire. The unsatisfactory wire contact can result is “arc flare” when contact is momentarily broken. The cast of typical welding wire is typically about 35–60 inches. If the cast is too small, the wire is highly sensitive to a helix thereby causing wire wobble when exiting a welding gun tip. When the cast is too large, the welding wire has difficulty in making reliable contact with the welding gun tip, and is also susceptible to conduit bending or becoming recast by small conduit radii as the wire is fed. This conduit bending or recasting of the welding wire can also result in wire wobble.
The wire can be manufactures either “no twist” or “with twist” when loosely wound in a wire package (e.g., drum, box, etc.). The traditional “with twist” wire drum is produced with a “dead block” technology and is intended to be used with a Lazy Susan turntable or dereeler which rotates the drum one turn per loop of wire as the wire is pulled. When the wire is pulled out of the drum, the twist induced in the wire by transforming a loop of wire from a circle into a straight line. The twist in the wire is cancelled by the Lazy Susan rotation of the package. The no-twist, or twist free package is intended to be used stationary. When the wire is laid in the package, the wire has a built-in twist of one rotation per loop. As such, as the wire is paid out of the package, the built-in twist cancels the twist induced by transforming a loop of wire into a straight line without having to rotate the package. Thus, manufacturers produce large containers of welding wire which must be paid out from the container without twisting, tangling and/or introducing unwanted canting into the wire itself.
In automatic and/or semi-automatic welding operations, a tremendous number of robotic welding stations are operable to consume welding wire from a package at each station as a continuous supply of wire to perform successive welding operations. The advent of this mass use of electric welding wire has caused tremendous research and development in improving the packaging for the bulk welding wire. A common package is a drum where looped welding wire is deposited in the drum as a wire stack, or body, of wire having a top surface with an outer cylindrical surface against the drum and an inner cylindrical surface defining a central bore. The central bore is often occupied by a cardboard cylindrical core as shown in Cooper U.S. Pat. No. 5,819,934, which is incorporated herein by reference. It is common practice for the drum to have an upper retainer ring that is used in transportation to stabilize the body of welding wire as it settles. This ring remains on the top of the welding wire to push downward by its weight so the wire can be pulled from the body of wire between the core and the ring. Each loop of wire has one turn of built-in twist so that when it is paid out, the twist introduced by releasing a loop of wire is canceled. Hence the wire is “twist-free” when it reaches the contact tip. The built-in twist causes the wire to spring up from the top of the stack when unrestrained. The weighted ring inhibits or prevents the wire from springing up which can result in the wire becoming tangled. Tangles are detrimental to the operation of the package since they cause down time of the robotic welding station. The most common tangle is a wire knot that forms between the ring and the hat. Such a knot is referred to as an e-script because of its shape. E-scripts in the wire can be attributed to several factors such as poor drive roll alignment in the feeder, inconsistent loop diameter, inconsistent fan-out of the loops, settling of the wire during transportation, and abuse in handling the drum of wire. An e-script tangle stops operation of the welder and must be removed. As a result, the tangling of the wire during the paying out of the welding wire results in the welding process having to be stopped, thus resulting in downtime. Such downtime reduces productivity efficiencies and increases production costs. This problem must be solved by manufacturers of welding wire as they sell the welding wire in quantities to be paid out for automatic and semi-automatic welding. This problem is compounded with the trend toward even larger packages with larger stock of welding wire to thereby reduce the time required for replacement of the supply container at the automatic or semiautomatic welding operation. Consequently, there is an increased demand for a container which is easily adapted to a large capacity and is constructed in a manner such that withdrawing of the welding wire from the container is accomplished smoothly without disturbing the natural flow of the welding wire or twisting the welding wire with adjacent convolutions.
Tangling of the wire can cause interruption of wire flow and drastically interrupt the welding operation. Thus, a large volume, high capacity storage or supply container for welding wire formed in wire stacks or coils must be so constructed that it assures against any catastrophic failure in the feeding of a wire to the welding operation and the container. Further the payout or withdrawing arrangement of the container must be assured that it does not introduce even minor distortions in the free flow of the welding wire to the welding operation. Consequently, there is a substantial demand for a container and withdrawing arrangement for large quantities of welding wire which not only prevents tangling and disruption of the supply of welding wire to the welding operation, but also prevents e-script tangles and other types of tangles under adverse conditions such as abuse in the handling and poor wire feeder drive roll alignment, together with excellent wire placement consistency and reliable wire-to-tip contact without arc flare. This can be accomplished by a more robust design of the package and payout mechanism.
The welding wire stored in the supply container is commonly in the form of a wire stack or coils having multiple layers of wire convolutions laid from bottom to top, with an inner diameter of the wire stack or coils being substantially smaller than the diameter of the container. Due to the inherent rigidity of the welding wire itself, the convolutions forming the layers are continuously under the influence of a force which tends to widen the diameter of the convolutions. However, as the welding wire is withdrawn from the container, the loosened wire portion tends to spring up and disturb or become entangled with other looped layers or with itself causing premature pop out of the wire loop to the inside bore, causing the top loop of the wire to more under lower wire loops, causing the wire loop to stretch and extend beyond the outside diameter of the wire stack and thereby fall down the outer periphery of the wire stack, and causing an expanded loop diameter of the wire resulting in the wire popping up above the outer periphery of the retaining ring thereby catching the ring. In such cases, it becomes difficult to withdraw the wire or feed the wire smoothly. In some of the prior containers, the wire is provided with a preselected twist when inserting the wire into the package in order to prevent torsional deformation of the wire which is being withdrawn axially from the non-rotating container. Consequently, the packaged wire of the wire stack or coils tends to spring up with a greater force. As a result, retainer rings or members are placed on the top of the wire stack or coils to hold the wire in the upper layers in place as it is withdrawn, convolution at a time, from the center opening of the wire stack or coils through the top opening of the supply container. Another defect in past wire packaging designs is the inability of the package to deal with excess and unsupported wire between the top of the hat and the retaining ring. After the wire leaves the top of the stack and escaping the constraint imposed by the retaining ring, the wire is essentially loose, unsupported and unstable until the wire reaches the top of the hat and enters the liner above the hat where the wire is again supported. The essentially loose, unsupported and unstable that is between the retaining ring and the top of the hat attempts to release any trapped energy in the wire. This is especially the case where there is excess wire coming from premature pop-out of wire loops from the retaining ring. The form the wire takes in attempting to release this excess energy is typically undesirable such as resulting is a knot. The loose, unsupported section of the wire can commonly result in the formation of e-script tangles in the wire.
In the past, substantial effort has been devoted to the prevention of the wire springing up which can result in a feeding error from the container. This feeding error is normally prevented by a center tube of cardboard placed in the wire stack or coils cavity so that all convolutions must be withdrawn from around the center tube. In the prior art, the ring itself contacts the inner surface of the container to prevent convolutions from springing above and around the outside of the retainer ring. In the past, the retainer ring generally rests upon the top of the wire stack or coils by gravity. The suspended float ring assembly is placed on top of the wire in the container to assist in keeping the wire from becoming tangled as it is fed out of the container. The suspended float ring assembly commonly includes an annular metal ring that surrounds the inner core and a plurality of flexible fingers or feathers that extend radially outwardly and slightly upwardly of the ring and into contact with the inner surface of the drum. These fingers can be constructed of plastic. The float ring is suspended, that is, it rests freely at the top of the coil of wire in the container. Some of the prior rings have had a series of flat spring steel fingers attached to the retainer ring. These fingers tightly ride against the drum to control the outside convolutions of wire. In some instances, a cardboard ring is cut to the desired shape with a slight interference with the drum wall. This ring is held on the top of the wire stack or coils by a weight which travels down the drum as the wire level is reduced.
All of these arrangements present difficulties when the wire is paid out from a package. Wire can be tangled on the outside of the ring and substantial drag can be imparted to the wire as it is being paid out or withdrawn from the container. As the wire is removed from the container, a part of the wire coil sprang upwardly and become caught between the float ring and the inner core, or wrap around the core, or forms a knot, thus causing a tangle. Also, the wire above the float ring would sometimes wrap around the inner core, particularly as the float ring assembly descended downwardly as the container emptied.
In an effort to provide better support of the wire, an improved retainer ring was developed as disclosed in U.S. Pat. No. 5,277,314. The retainer ring or retainer member included a generally flat outer portion with an outer periphery fitting into a set diameter of the inner wall of the container and had a number of projecting lobe portions whereby the outer periphery of the retainer ring contained alternate areas that were closer to and then farther away from the outer wall of the container when the retainer ring was resting on the upper surface or top of the hollow, cylindrical wire stack or coils of welding wire. The retaining ring also had an inner bell mouthed portion defining an innermost wire extraction opening wherein the convolutions of wire are pulled up through the bell mouthed portion which extended upwardly toward the outlet guide in the top cover or “hat” of the container. The convolutions of wire, as they were pulled from the wire stack or coils, move inwardly toward and into the center cavity of the wire stack or coils and then upwardly through the bell mouth portion toward the exit guide in the container hat. The wire extraction opening defined by the upper end of the bell mouthed portion of the retainer ring included a diameter substantially smaller than the selected diameter of the wire stack or coils itself so that the wire must moved inwardly before it can move upwardly. By using this bell mouthed concept, the upward movement of the convolutions from the wire stack or coils did not have better support against other convolutions and does not have better support drag along the bottom of the retainer ring as the convolutions from the upper layer were moved inwardly and then upwardly to the outlet guide in the cover or hat of the supply container.
Another prior art retaining ring is disclosed in U.S. Pat. No. 5,758,834. The wire control ring is mounted at the upper part of the inner core and provided with finger and an arrangement that prevents the wire from entering into the space between the ring and the core. The wire control ring has an annular metal ring having an inner diameter which is slightly greater than the outer diameter of the drum's inner core, and an outer diameter which permits the unobstructed removal of wire from the drum. A set of three or four fingers or feathers attached to the ring extend outwardly and slightly upwardly into contact with the inner surface of the drum. The width of these fingers is significantly greater than the width of the prior art feathers to insure that the wire is forced against the inner surface of the drum as it is pulled from the drum and removed. The stiffness of the feathers is such that the wire cannot by itself uncoil and exit the drum, but it not so stiff that the resistance to wire movement from the drum adversely affects the wire feeding process. A diverter member prevents wire from inadvertently entering the space between the ring and the drum's inner core.
Although these retaining rings have reduced the incidence of tangling of the welding wire paid out from a container of welding wire, small twists or e-scripts still occur during payout of the welding wire. These twists or e-scripts in the wire can result insubstantial downtime of the welding process in order to untangle the welding wire.
In view of the continuing problems associated with weld wire payout from wire containers and the periodic occurrence of twists or e-scripts in the welding wire during payout, the remains a continued need for a welding wire payout arrangement for wire containers which reduces the occurrence of wire tangles and twists or e-scripts in the welding wire during payout of the welding wire from a wire container.